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(单词翻译:双击或拖选)
Narwhals aren’t fish, they’re mammals--a rare type of whale. They have a famous spiraled tusk1. The tusk, which is commonly misconceived for a horn, is actually an elongated2 tooth. Only male narwhals grow tusks3, which can be over six to almost ten feet long-more than half their body length. What Is The Function Of The Tusk? There is patchy evidence for several different hypotheses. Since only males grow tusks, it could have evolved in response to sexual selection. Like the tails of male peacocks, the tusk could be used to attract and impress females and intimidate4 rival males.
点击收听单词发音
1 tusk | |
n.獠牙,长牙,象牙 | |
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2 elongated | |
v.延长,加长( elongate的过去式和过去分词 ) | |
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3 tusks | |
n.(象等动物的)长牙( tusk的名词复数 );獠牙;尖形物;尖头 | |
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4 intimidate | |
vt.恐吓,威胁 | |
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